Personal lubricants for intimate contact are well known. In recent years, it has become increasingly popular to add various functional agents to personal lubricant compositions in order to, for example, enhance pleasurable feelings during sexual activity and/or to heighten sexual arousal. Examples of such products include K-Y® Warming Liquid and Durex® Play Tingling. K-Y® Warming Liquid is a water-soluble, anhydrous composition that warms on contact while providing lubrication. Durex® Play Tingling is a water-soluble composition with a unique blend of agents that warms, cools and tingles while providing lubrication.
Using condoms containing lubricants which include sensorial agents has also been proposed. Producing such lubricated condoms is somewhat challenging, particularly if the lubricant is to be applied both on the inside and on the outside of the condom. Conventional machinery used in condom manufacture mandates that the lubricant composition have relatively tight specifications, for example, in terms of viscosity, tackiness and stringiness, as well as providing the desired degree of lubricity.
Personal lubricants comprising functional agents are designed to cause physiological or physical changes in the area to which they are applied. These functional agents range from agents that self-warm when exposed to moisture, e.g. polyols, agents that act on nerve endings to simulate a perceived sensation such as warming, cooling and/or tingling, and agents that could in sufficient quantity increase localized blood flow, e.g. vasodilators.
Self-warming lubricants are known in the art. They generate heat or warming when placed in contact with moisture on the human body, e.g. K-Y® Warming Liquid. The warming effect is created by a phenomenon known as heat of dilution; some agents when diluted with water release energy in the form of heat; e.g., polyethylene glycol. When blended with an anhydrous composition, the product upon dilution provides a slight warming effect.
Thermoreceptors belong to the class of transient receptor potential (TRP). TRP subfamily V, members 1 to 3 (TRPV1 to TRPV3) are activated by heat. TRPV4, TRP subfamily A, member 1 (TRPA1) and TRP melastatin 8 (TRPM8) are activated by cold. The cold receptor TRPA1 when activated by noxious cold produces a pain-like sensation, which paradoxically produces a human sensorial effect often described as “hot”.
Lubricants that provide a perceived sensation are also known in the art. For example, Trojan® Fire & Ice® condom comprises a lubricant composition on the condom that utilizes vanillyl butyl ether (VBE) to simulate a perceived warming sensation and menthol to simulate a perceived cooling sensation. Chemical warming agents (such as VBE) bind TRPV1 on sensory neurons. Chemical cooling agents (such as menthol) bind to TRPM8 or cold and menthol receptor 1 (CMR1).
However, some agents like VBE, menthol, vasodilators, and various natural extracts, e.g. sichuan, jambu, ginger, maca, etc., are known to be skin irritants. Such compositions have the disadvantage of causing irritation to the mucosa, which can be problematic in relation to the vaginal or oral mucosa as irritation may disrupt the sexual experience. Accordingly, there remains a need to deliver a sensory stimuli using a personal lubricant while minimizing the effect of irritation.